In conventional cellular networks, a core functions as a server for many client base stations. The core is typically responsible for authentication, authorization, and accounting, anchoring point of the user, ip address allocation, handling addresses from an external interface point of view, idle state and mobility handler. Some application servers, for example video servers and SIP servers, may also reside in the core. In gsm/GERAN the core is termed CN (core network) and includes GGSN, SGSN, HLR and MSC. in UMTS/UTRAN the core is also termed CN.
Methods for linking stationery cores are known.
GRE (Generic Routing Encapsulation) is a known tunneling protocol operative to encapsulate various network layer protocols inside virtual point-to-point links over an Internet Protocol internetwork.
A GRE packet header structure is represented in FIG. 1a (prior art).
Tunnels are operative to transmit a first computer network protocol encapsulated inside a second network protocol. Use of tunneling to carry a payload over an incompatible delivery-network, or to provide secure delivery via a non-secure network, is known. GRE tunnels are used e.g. to carry IP packets with private addresses over the Internet using delivery packets with public IP addresses.
The disclosures of all publications and patent documents mentioned in the specification and materials appended thereto, and of the publications and patent documents cited therein directly or indirectly, are hereby incorporated by reference.